Ankle Fractures Involving the Fibula Proximal to the Distal Tibiofibular Syndesmosis

Abstract

Thirty-two cases of ankle fractures associated with fibular fractures above the distal tibiofibular syndesmosis were studied. All were treated with open reduction and internal fixation. The average follow-up was 25 months. The results of the postoperative evaluation were rated, based on subjective clinical criteria, as good, fair, and poor. According to the Lauge-Hansen classification, there were 17 (53%) cases of supination-external rotation injury (2 stage 2 and 15 stage 4), 9 (28%) cases of stage 3 pronation-abduction injury, and 6 (19%) cases of pronation-external rotation injury (3 stage 3 and 3 stage 4). All cases could be classified as Weber type C or as suprasyndesmotic, fibular diaphyseal fracture (44-C) according to the Orthopaedic Trauma Association classification. In 18 (56%) cases, the fracture was associated with ankle dislocation. There were seven (22%) open fractures (two grade I, four grade II, and one grade IIIA). Syndesmotic screws were used in 23 (72%) cases (12 supination-external rotation injury, 6 pronation-external rotation injury, and 5 pronation-abduction injury). The syndesmotic screw was removed after an average of 9 weeks. Four (13%) nonunions and two (6%) delayed unions of the fibula were treated with bone grafting and/or hardware revision and eventually healed. Three of the nonunions had poor clinical results because of degenerative ankle joint arthritis in two (one of them ended in arthrodesis) and deep infection, which was eventually cured, in the third. The fourth nonunion had a fair result. One of the delayed unions had a fair result (an obese patient) and the other had a good result. Two patients developed deep infections; one ended in gangrene and amputation in a diabetic patient, and the other was a patient with fibular nonunion that eventually healed. Three patients had superficial infections that were treated successfully. Of the 32 cases, 23 (72%) showed good results, 4 (13%) showed fair results, and 5 (16%) showed poor results. The cases with poor results included three fibular nonunions, one deep infection, and one recurrent superficial infection and wound dehiscence after hardware removal. A syndesmotic screw is usually needed in cases of fracture-dislocations. Two patients with occult fibular nonunions developed diastasis of the syndesmosis after removal of the syndesmotic screw. It was found that reduction and temporary pinning of the distal tibiofibular joint helps achieve fibular length, which is crucial to restoring the biomechanics of the ankle joint. It seems advisable not to remove the syndesmotic screw until there are signs of healing of fibular fracture to avoid diastasis of the distal tibiofibular joint. Bone grafting should be considered in high energy fractures with comminution. These complex injuries are associated with higher rates of complications. Poor results can be attributed to fracture factors, e.g., open fractures, infections; patient factors, e.g., obesity, lowered immunity as in diabetes, and noncompliance; and iatrogenic factors, e.g., early removal of syndesmotic screws.